/*
 * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/DefaultHttpMethodRetryHandler.java,v 1.3 2004/12/20 11:47:46 olegk Exp $
 * $Revision: 480424 $
 * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
 *
 * ====================================================================
 *
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.NoRouteToHostException;
import java.net.UnknownHostException;

/**
 * The default {@link HttpMethodRetryHandler} used by {@link HttpMethod}s.
 * 
 * @author Michael Becke
 * @author <a href="mailto:oleg -at- ural.ru">Oleg Kalnichevski</a>
 */
public class DefaultHttpMethodRetryHandler implements HttpMethodRetryHandler {

	private static Class SSL_HANDSHAKE_EXCEPTION = null;

	static {
		try {
			SSL_HANDSHAKE_EXCEPTION = Class
					.forName("javax.net.ssl.SSLHandshakeException");
		} catch (ClassNotFoundException ignore) {
		}
	}
	/** the number of times a method will be retried */
	private int retryCount;

	/**
	 * Whether or not methods that have successfully sent their request will be
	 * retried
	 */
	private boolean requestSentRetryEnabled;

	/**
	 * Creates a new DefaultHttpMethodRetryHandler.
	 * 
	 * @param retryCount
	 *            the number of times a method will be retried
	 * @param requestSentRetryEnabled
	 *            if true, methods that have successfully sent their request
	 *            will be retried
	 */
	public DefaultHttpMethodRetryHandler(int retryCount,
			boolean requestSentRetryEnabled) {
		super();
		this.retryCount = retryCount;
		this.requestSentRetryEnabled = requestSentRetryEnabled;
	}

	/**
	 * Creates a new DefaultHttpMethodRetryHandler that retries up to 3 times
	 * but does not retry methods that have successfully sent their requests.
	 */
	public DefaultHttpMethodRetryHandler() {
		this(3, false);
	}

	/**
	 * Used <code>retryCount</code> and <code>requestSentRetryEnabled</code> to
	 * determine if the given method should be retried.
	 * 
	 * @see HttpMethodRetryHandler#retryMethod(HttpMethod, IOException, int)
	 */
	public boolean retryMethod(final HttpMethod method,
			final IOException exception, int executionCount) {
		if (method == null) {
			throw new IllegalArgumentException("HTTP method may not be null");
		}
		if (exception == null) {
			throw new IllegalArgumentException(
					"Exception parameter may not be null");
		}
		// HttpMethod interface is the WORST thing ever done to HttpClient
		if (method instanceof HttpMethodBase) {
			if (((HttpMethodBase) method).isAborted()) {
				return false;
			}
		}
		if (executionCount > this.retryCount) {
			// Do not retry if over max retry count
			return false;
		}
		if (exception instanceof NoHttpResponseException) {
			// Retry if the server dropped connection on us
			return true;
		}
		if (exception instanceof InterruptedIOException) {
			// Timeout
			return false;
		}
		if (exception instanceof UnknownHostException) {
			// Unknown host
			return false;
		}
		if (exception instanceof NoRouteToHostException) {
			// Host unreachable
			return false;
		}
		if (SSL_HANDSHAKE_EXCEPTION != null
				&& SSL_HANDSHAKE_EXCEPTION.isInstance(exception)) {
			// SSL handshake exception
			return false;
		}
		if (!method.isRequestSent() || this.requestSentRetryEnabled) {
			// Retry if the request has not been sent fully or
			// if it's OK to retry methods that have been sent
			return true;
		}
		// otherwise do not retry
		return false;
	}

	/**
	 * @return <code>true</code> if this handler will retry methods that have
	 *         successfully sent their request, <code>false</code> otherwise
	 */
	public boolean isRequestSentRetryEnabled() {
		return requestSentRetryEnabled;
	}

	/**
	 * @return the maximum number of times a method will be retried
	 */
	public int getRetryCount() {
		return retryCount;
	}
}
